But there’s much more to this story. The maps we have made show that the election was not just about red and blue states. What’s actually going on is that the division between red and blue America is mostly about a split among richer voters.

To picture this, imagine two alternative universes for the 2012 election. In the first, only individuals making less than $50,000 a year can vote; in the second, only those making more than $100,000 a year can. Based on exit polls from Election Day, we have a decent idea of how these scenarios would play out.

In the first universe, Barack Obama wins in a 1984-style landslide, with a near sweep of the Electoral College and around 60 percent of the popular vote.

In the second universe, Mitt Romney wins with a healthy 54 percent of the popular vote. Though he still carries the red states, a landslide remains out of his grasp — wealthy voters in blue states like New York and California still support Obama by comfortable margins. We’ll come back to this thought in a moment.

The maps above show the election results for four income groups as measured by exit polls (with blanks for the states that were not polled).

Remarkably, this same pattern has occurred in every presidential contest over the past twenty years. . . .

In other words, contrary to what you have heard, there’s only a strong red America-blue America split toward the top of the income distribution. Toward the bottom, the electoral map is a sea of blue.

Why does this happen? Our research on opinion poll data from earlier elections finds that lower-income Americans tend to vote based on economic issues, while richer voters consider social issues as well as economics in their voting decisions. This is sometimes called post-materialism: the idea that, as individuals or groups become more comfortable, they can afford to think beyond their immediate needs.

The so-called culture war between red and blue America is concentrated in the upper half of the income distribution, and voting patterns reflect this.